Wash and dry collards and chard; remove any large stems. Stack the leaves and roll tightly into a tube. Using a sharp knife, slice very thin ribbons (as thin as you can) perpendicular to the roll; set aside.In a large skillet over medium heat, place olive oil, butter, garlic and lemon peel/ zest; cook about 1 minute, then add greens. If mixture seems too dry, add 1 tablespoon olive oil.Using tongs, mix greens into flavored oil, then reduce heat to low so garlic doesn’t burn. Sprinkle in salt, keep stirring the greens 2–3 minutes, then remove from heat and add lemon juice. Taste for seasoning and top with nuts and rosemary, if using.